CN108471299B - Multiplexer, transmission device, reception device, and impedance matching method for multiplexer - Google Patents

Multiplexer, transmission device, reception device, and impedance matching method for multiplexer Download PDF

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CN108471299B
CN108471299B CN201810156157.1A CN201810156157A CN108471299B CN 108471299 B CN108471299 B CN 108471299B CN 201810156157 A CN201810156157 A CN 201810156157A CN 108471299 B CN108471299 B CN 108471299B
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terminal
elastic wave
wave filter
multiplexer
filter
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CN108471299A (en
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高峰裕一
高井努
丰田祐二
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Murata Manufacturing Co Ltd
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Murata Manufacturing Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/005—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
    • H04B1/0053—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges with common antenna for more than one band
    • H04B1/0057—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges with common antenna for more than one band using diplexing or multiplexing filters for selecting the desired band
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/38—Impedance-matching networks
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/64—Filters using surface acoustic waves
    • H03H9/6406—Filters characterised by a particular frequency characteristic
    • H03H9/6413—SAW comb filters
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/0004—Impedance-matching networks
    • H03H9/0009—Impedance-matching networks using surface acoustic wave devices
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/0004—Impedance-matching networks
    • H03H9/0014—Impedance-matching networks using bulk acoustic wave devices
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/64—Filters using surface acoustic waves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/64—Filters using surface acoustic waves
    • H03H9/6489—Compensation of undesirable effects
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/70—Multiple-port networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source
    • H03H9/703—Networks using bulk acoustic wave devices
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/70—Multiple-port networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source
    • H03H9/72—Networks using surface acoustic waves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/70—Multiple-port networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source
    • H03H9/72—Networks using surface acoustic waves
    • H03H9/725—Duplexers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/02—Transmitters
    • H04B1/04—Circuits
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/16—Circuits
    • H04B1/1638—Special circuits to enhance selectivity of receivers not otherwise provided for
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40—Circuits
    • H04B1/50—Circuits using different frequencies for the two directions of communication
    • H04B1/52—Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/20—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other
    • H04B3/21—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other using a set of bandfilters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/02—Transmitters
    • H04B1/04—Circuits
    • H04B1/0458—Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/16—Circuits
    • H04B1/18—Input circuits, e.g. for coupling to an antenna or a transmission line
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/02—Transmitters
    • H04B1/04—Circuits
    • H04B2001/0408—Circuits with power amplifiers

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
  • Transceivers (AREA)

Abstract

Provided are a multiplexer, a transmission device, a reception device, and an impedance matching method for the multiplexer, which can reduce insertion loss even when the characteristic impedance is different between the transmission/reception terminal side and the antenna terminal side of a surface acoustic wave filter. A multiplexer (1) is provided with: filters (11-14); a common terminal (50) for connecting an inductive element (31) between a connection path with the antenna element (2) and a reference terminal and for connecting a capacitive element (32) in series with the connection path; and an inductance element (21), wherein the input terminal of the filter (12) of the filters (11-14) is connected to the common terminal (50) via the inductance element (21) and is connected to the parallel resonator, and wherein one of the input terminals and the output terminals of the transmission-side filters (11, 13) and the reception-side filter (14) other than the reception-side filter (12) of the filters (11-14), which is close to the antenna element (2), is connected to the common terminal (50) and is connected to the series resonator.

Description

Multiplexer, transmission device, reception device, and impedance matching method for multiplexer
Technical Field
The present invention relates to a multiplexer including an elastic wave filter, a transmission device, and a reception device.
Background
In recent years, there is a demand for a mobile phone that can support a plurality of frequency bands and a plurality of radio systems, so-called multi-band and multi-mode, in one terminal. In order to cope with this, a multiplexer for demultiplexing a high-frequency signal having a plurality of radio carrier frequencies is disposed directly below one antenna. As the plurality of band pass filters constituting the multiplexer, elastic wave filters characterized by low loss in the pass band and steepness of the pass characteristic around the pass band are used.
Patent document 1 discloses a surface acoustic wave device (SAW duplexer) having a structure in which a plurality of surface acoustic wave filters are connected. Specifically, an inductance element is connected in series between the antenna element and the connection path between the antenna terminal and the reception-side surface acoustic wave filter and the transmission-side surface acoustic wave filter, in order to match the impedance between the antenna element and the antenna terminal. The inductance element can make the complex impedance of the surface acoustic wave filter, as viewed from the antenna terminal to which the plurality of surface acoustic wave filters having capacitance are connected, close to the characteristic impedance. This is considered to prevent the degradation of the insertion loss.
Prior art documents
Patent document
Patent document 1: international publication No. 2016/208670
In recent years, when a transmission terminal of a transmission-side surface acoustic wave filter is connected to a PA (Power Amplifier) and a reception terminal of a reception-side surface acoustic wave filter is connected to an LNA (Low Noise Amplifier), characteristic impedances on the transmission terminal of the transmission-side surface acoustic wave filter and the reception terminal of the reception-side surface acoustic wave filter are sometimes designed to match the PA and the LNA, respectively, in order to reduce the number of matching elements for impedance matching. However, since the characteristic impedance of the terminal on the antenna side of the transmission-side surface acoustic wave filter and the reception-side surface acoustic wave filter is 50 Ω, the characteristic impedance may be different between the transmission terminal or the reception terminal side of the surface acoustic wave filter and the antenna terminal side. In this case, the surface acoustic wave device and the impedance matching method described in patent document 1 have a problem that impedance cannot be sufficiently matched for each terminal, and insertion loss increases.
Disclosure of Invention
Problems to be solved by the invention
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a multiplexer, a transmission device, and a reception device capable of reducing insertion loss in the pass band of each elastic wave filter even when the characteristic impedance is different between the transmission terminal or the reception terminal side of the surface acoustic wave filter and the antenna terminal side.
Means for solving the problems
In order to achieve the above object, a multiplexer according to an aspect of the present invention transmits and receives a plurality of high frequency signals via an antenna element, the multiplexer including: a plurality of elastic wave filters having different pass bands from each other; a common terminal to which at least one 1 st circuit element is connected between a connection path with the antenna element and a reference terminal, and to which at least one 2 nd circuit element is connected in series; and a1 st inductance element, each of the plurality of elastic wave filters including at least one of a series resonator connected between an input terminal and an output terminal, and a parallel resonator connected between a connection path connecting the input terminal and the output terminal and a reference terminal, wherein one of an input terminal and an output terminal of one of the plurality of elastic wave filters, which is close to the antenna element, is connected to the common terminal via the 1 st inductance element connected to the one of the input terminal and the output terminal, and is connected to the parallel resonator, and wherein one of an input terminal and an output terminal of another one of the plurality of elastic wave filters, which is close to the antenna element, is connected to the common terminal, and is connected to the series resonator.
With this configuration, the degree of freedom of impedance matching can be improved according to the type, characteristics, connection position, combination, and the like of the 1 st circuit element and the 2 nd circuit element. Thus, even when the characteristic impedance is different between the transmission terminal or the reception terminal side and the antenna terminal side of the surface acoustic wave filter, the impedance can be sufficiently matched to each terminal. Therefore, the insertion loss in the pass band of each elastic wave filter constituting the multiplexer can be reduced. Therefore, it is not necessary to provide a matching element between each elastic wave filter and the PA or LNA, and a high-frequency circuit having a simple configuration can be realized.
Further, the 1 st inductance element may be connected to one terminal of the one elastic wave filter close to the antenna element, so that impedance of a frequency band other than the self frequency band of the one elastic wave filter becomes inductive.
This makes it possible to easily adjust the complex impedance to the characteristic impedance by using the complex conjugate relationship. Therefore, even when the characteristic impedance is different between the transmission terminal or the reception terminal side and the antenna terminal side of the surface acoustic wave filter, the impedance can be sufficiently matched for each terminal. Therefore, the insertion loss in the pass band of each elastic wave filter constituting the multiplexer can be reduced.
The 1 st circuit element or the 2 nd circuit element connected on the side closest to the common terminal may be an inductance element.
Thus, when the real part of the characteristic impedance as viewed from the common terminal side is less than 50 Ω and the characteristic impedance in the pass band of the multiplexer is in quadrant 3 or quadrant 4 on the smith chart, the characteristic impedance can be sufficiently matched to each terminal. Therefore, particularly when the real part of the characteristic impedance as viewed from the common terminal side is less than 50 Ω and the characteristic impedance in the pass band of the multiplexer is in quadrant 3 or quadrant 4 on the smith chart, the insertion loss in the pass band of each elastic wave filter constituting the multiplexer can be reduced.
In addition, the 1 st circuit element may be an inductance element, and the 2 nd circuit element may be a capacitance element.
Thus, when the real part of the characteristic impedance as viewed from the common terminal side is less than 50 Ω and the characteristic impedance in the pass band of the multiplexer is in quadrant 4 on the smith chart, the characteristic impedance can be sufficiently matched to each terminal. Therefore, in particular, when the real part of the characteristic impedance as viewed from the common terminal side is less than 50 Ω and the characteristic impedance in the pass band of the multiplexer is in quadrant 4 in the smith chart, the insertion loss in the pass band of each elastic wave filter constituting the multiplexer can be reduced.
In addition, the 1 st circuit element may be a capacitive element, and the 2 nd circuit element may be an inductive element.
Thus, when the real part of the characteristic impedance as viewed from the common terminal side is less than 50 Ω and the characteristic impedance in the pass band of the multiplexer is in quadrant 3 on the smith chart, and when the real part of the characteristic impedance as viewed from the common terminal side is 50 Ω or more and the characteristic impedance in the pass band of the multiplexer is in quadrant 3 or quadrant 4 on the smith chart, the characteristic impedance can be sufficiently matched to each terminal. Therefore, in particular, when the real part of the characteristic impedance as viewed from the common terminal side is less than 50 Ω and the characteristic impedance in the pass band of the multiplexer is at quadrant 3 in the smith chart, and when the real part of the characteristic impedance as viewed from the common terminal side is 50 Ω or more and the characteristic impedance in the pass band of the multiplexer is at quadrant 3 or quadrant 4 in the smith chart, the insertion loss in the pass band of each elastic wave filter constituting the multiplexer can be reduced.
Further, the characteristic impedances of the terminals on the opposite side of the input terminal and the output terminal of the plurality of elastic wave filters from the terminal close to one of the antenna elements may be different from each other.
In this way, since the characteristic impedance of each elastic wave filter constituting the multiplexer can be adjusted, the insertion loss in the pass band of the characteristic impedance of each elastic wave filter can be appropriately reduced.
Further, the other elastic wave filter, which requires isolation from the one elastic wave filter, among the plurality of elastic wave filters may have a 2 nd inductance element in series or in parallel at a terminal on a side opposite to a terminal close to one side of the antenna element.
Thus, the isolation of the elastic wave filter provided with the 2 nd inductance element can be increased by utilizing the coupling between the 2 nd inductance element and the other inductance element.
Further, a complex impedance in a predetermined pass band when the single elastic wave filter is viewed through the 1 st inductance element in a state where the 1 st inductance element and one of the input terminal and the output terminal of the one elastic wave filter which is close to the antenna element are connected in series, and a complex impedance in the predetermined pass band when the elastic wave filter other than the one elastic wave filter is viewed from the side of one of the terminals which is close to the antenna element and is connected to the common terminal in a state where one of the input terminal and the output terminal of the elastic wave filter other than the one elastic wave filter which is close to the antenna element is connected to the common terminal may be in a complex conjugate relationship.
This makes it possible to match the complex impedance viewed from the common terminal of the multiplexer having a circuit obtained by combining a circuit in which the 1 st inductance element and one elastic wave filter are connected in series and a circuit in which elastic wave filters other than the one elastic wave filter are connected in parallel via the common terminal, with the characteristic impedance while securing a low loss factor in the pass band. Further, by connecting the 1 st inductance element in series between the common terminal and the antenna element, the complex impedance of the multiplexer viewed from the common terminal can be finely adjusted toward the inductive side.
Further, the piezoelectric substrate that constitutes each of the plurality of surface acoustic wave filters may include: a piezoelectric film having an IDT (InterDigital Transducer) electrode formed on one surface; a high acoustic velocity support substrate that propagates a bulk acoustic velocity higher than an elastic acoustic velocity propagating in the piezoelectric film; and a low sound velocity film disposed between the high sound velocity support substrate and the piezoelectric film, the low sound velocity film propagating a bulk sound velocity lower than an elastic sound velocity propagating through the piezoelectric film.
When the 1 st inductance element or the like is connected in series to the common terminal side of one elastic wave filter, a circuit element such as an inductance element or a capacitance element is added to obtain impedance matching between the plurality of elastic wave filters. In this case, it is assumed that the Q values of the resonators are equivalently small. However, according to the laminated structure of the present piezoelectric substrate, the Q value of each resonator can be maintained at a high value. Therefore, an elastic wave filter having a low loss factor in a frequency band can be formed.
Further, the multiplexer may include, as the plurality of elastic wave filters: the elastic wave filter of 1 st, having a1 st pass band, outputting a transmission signal to the antenna element; 2 the elastic wave filter having a 2 nd pass band adjacent to the 1 st pass band, receiving a signal input from the antenna element; the elastic wave filter of claim 3 having a 3 rd pass band located on a lower frequency side than the 1 st pass band and the 2 nd pass band, and outputting a transmission signal to the antenna element; and the 4 th elastic wave filter having a 4 th passband located at a higher frequency side than the 1 st passband and the 2 nd passband, wherein a reception signal is input from the antenna element, and the one elastic wave filter to which the 1 st inductance element is connected in series is at least one of the 2 nd elastic wave filter and the 4 th elastic wave filter.
A transmission device according to an aspect of the present invention is a transmission device that receives a plurality of high-frequency signals having mutually different carrier frequency bands, filters the plurality of high-frequency signals, and wirelessly transmits the filtered high-frequency signals from a common antenna element, the transmission device including: a plurality of transmitting elastic wave filters that receive the plurality of high-frequency signals from the transmitting circuit and pass only a predetermined frequency band; and a common terminal to which at least one 1 st circuit element is connected between a connection path to the antenna element and a reference terminal and at least one 2 nd circuit element is connected in series to the connection path, wherein each of the plurality of transmission elastic wave filters includes at least one of a series resonator connected between an input terminal and an output terminal and a parallel resonator connected between a connection path connecting the input terminal and the output terminal and a reference terminal, wherein an output terminal of one transmission elastic wave filter is connected to the common terminal via an inductance element connected to the output terminal and the common terminal and is connected to the parallel resonator, and output terminals of transmission elastic wave filters other than the one transmission elastic wave filter are connected to the common terminal, and is connected to the series resonator among the series resonators and the parallel resonators.
A receiving apparatus according to an aspect of the present invention is a receiving apparatus that receives a plurality of high-frequency signals having different carrier frequency bands via an antenna element, and that demultiplexes and outputs the plurality of high-frequency signals to a receiving circuit, the receiving apparatus including: a plurality of reception elastic wave filters that input the plurality of high-frequency signals from the antenna element and pass only a predetermined frequency band; and a common terminal to which at least one 1 st circuit element is connected between a connection path to the antenna element and a reference terminal and at least one 2 nd circuit element is connected in series to the connection path, wherein each of the plurality of reception elastic wave filters includes at least one of a series resonator connected between an input terminal and an output terminal and a parallel resonator connected between a connection path connecting the input terminal and the output terminal and a reference terminal, wherein one of the plurality of reception elastic wave filters has an input terminal connected to the common terminal via an inductance element connected to the input terminal and the common terminal and is connected to the parallel resonator, and wherein input terminals of reception elastic wave filters other than the one reception elastic wave filter are connected to the common terminal, and is connected to the series resonator among the series resonators and the parallel resonators.
In addition, an aspect of the present invention provides an impedance matching method for a multiplexer that transmits and receives a plurality of high-frequency signals via an antenna element, the method comprising: adjusting a plurality of elastic wave filters having different pass bands such that complex impedances in pass bands of the other elastic wave filters become a short-circuited state when the single elastic wave filter is viewed from one of an input terminal and an output terminal of the single elastic wave filter, and complex impedances in pass bands of the other elastic wave filters become an open-circuited state when the single elastic wave filter is viewed from one of the input terminal and the output terminal of the elastic wave filter other than the single elastic wave filter, among the plurality of elastic wave filters; adjusting an inductance value of the filter-matching inductance element so that a complex impedance when the one elastic wave filter is viewed from the filter-matching inductance element side when the one elastic wave filter is connected in series to the filter-matching inductance element and a complex impedance when the other elastic wave filter is viewed from the common terminal side when the other elastic wave filter other than the one elastic wave filter is connected in parallel to the common terminal are in a complex conjugate relationship; adjusting at least one 1 st circuit element connected between a connection path between the antenna element and the common terminal and a reference terminal, and at least one 2 nd circuit element connected in series to a connection path between the antenna element and the common terminal so that a complex impedance seen from the common terminal of a synthesis circuit in which the one elastic wave filter is connected to the common terminal via the filter-matching inductance element and the other elastic wave filters are connected in parallel to the common terminal is matched with a characteristic impedance, wherein the adjusting of the plurality of elastic wave filters includes at least one of a series resonator connected between an input terminal and an output terminal, and a parallel resonator connected between a connection path connecting the input terminal and the output terminal and a reference terminal, in the one elastic wave filter, the parallel resonator and the series resonator are arranged such that the parallel resonator is connected to the filter matching inductance element, and in the other elastic wave filter, the parallel resonator and the series resonator are arranged such that the series resonator out of the parallel resonator and the series resonator is connected to the common terminal.
This can improve the degree of freedom of impedance matching according to the type, characteristics, connection position, combination, and the like of the 1 st circuit element and the 2 nd circuit element. Therefore, even when the characteristic impedance is different between the transmission terminal or the reception terminal side and the antenna terminal side of the surface acoustic wave filter, the impedance can be sufficiently matched for each terminal.
Effects of the invention
According to the multiplexer, the transmission device, and the reception device of the present invention, even when the characteristic impedances are different on the transmission terminal or the reception terminal side and the antenna terminal side of the surface acoustic wave filter, the insertion loss in the pass band of each elastic wave filter can be reduced.
Drawings
Fig. 1 is a circuit configuration diagram of a multiplexer according to embodiment 1.
Fig. 2 is a plan view and a cross-sectional view schematically showing a resonator of the surface acoustic wave filter according to embodiment 1.
Fig. 3A is a circuit configuration diagram of a transmission side filter of Band25 constituting the multiplexer according to embodiment 1.
Fig. 3B is a circuit configuration diagram of the receiving side filter of Band25 constituting the multiplexer according to embodiment 1.
Fig. 3C is a circuit configuration diagram of the transmission side filter of Band66 constituting the multiplexer according to embodiment 1.
Fig. 3D is a circuit configuration diagram of the receiving side filter of Band66 constituting the multiplexer according to embodiment 1.
Fig. 4 is a schematic plan view showing an electrode structure of a longitudinally coupled surface acoustic wave filter according to embodiment 1.
Fig. 5A is a graph comparing the pass characteristics of the transmission side filters of Band25 according to embodiment 1 and the comparative example.
Fig. 5B is a graph comparing the pass characteristics of the receiving side filters of Band25 according to embodiment 1 and the comparative example.
Fig. 5C is a graph comparing the pass characteristics of the transmission side filters of Band66 according to embodiment 1 and the comparative example.
Fig. 5D is a graph comparing the pass characteristics of the receiving side filters of Band66 according to embodiment 1 and the comparative example.
Fig. 6A is a smith chart showing the complex impedance observed from the transmission output terminal of the transmission side filter alone of Band25 according to embodiment 1.
Fig. 6B is a smith chart showing the complex impedance observed from the reception input terminal of the reception side filter alone of Band25 according to embodiment 1.
Fig. 6C is a smith chart showing the complex impedance observed from the transmission output terminal of the transmission side filter alone of Band66 according to embodiment 1.
Fig. 6D is a smith chart showing the complex impedance observed from the reception input terminal of the reception side filter alone of Band66 according to embodiment 1.
Fig. 7 is a smith chart showing complex impedance observed from the common terminal of the circuit cell in which all filters other than the reception side filter of Band25 according to embodiment 1 are connected in parallel via the common terminal, and a smith chart showing complex impedance observed from the inductance element side of the circuit cell in which the reception side filter of Band25 according to embodiment and the inductance element are connected in series.
Fig. 8A is a smith chart showing complex impedances observed from the common terminal of a circuit in which 4 filters according to embodiment 1 are connected in parallel via the common terminal.
Fig. 8B is a smith chart showing complex impedances when 4 filters according to embodiment 1 are connected in parallel via a common terminal and an inductance element is connected between a connection path between the common terminal and the antenna and a reference terminal.
Fig. 9 is a circuit configuration diagram showing an example of the multiplexer according to embodiment 2.
Fig. 10 is a diagram for explaining the relationship between the complex impedance seen from the common terminal in the multiplexer according to embodiment 2, and the type and connection position of the circuit element connected between the common terminal and the antenna element.
Fig. 11A is a diagram showing an example of the type and connection position of circuit elements connected between the common terminal and the antenna element in the multiplexer according to embodiment 2.
Fig. 11B is a diagram showing another example of the types and connection positions of circuit elements connected between the common terminal and the antenna element in the multiplexer according to embodiment 2.
Fig. 11C is a diagram showing another example of the types and connection positions of circuit elements connected between the common terminal and the antenna element in the multiplexer according to embodiment 2.
Fig. 11D is a diagram showing another example of the types and connection positions of circuit elements connected between the common terminal and the antenna element in the multiplexer according to embodiment 2.
Fig. 12 is a circuit configuration diagram showing another example of the multiplexer according to embodiment 2.
Fig. 13A is a diagram showing a configuration of a multiplexer according to modification 1 of the embodiment.
Fig. 13B is a diagram showing a configuration of a multiplexer according to modification 2 of the embodiment.
Fig. 14 is an operation flowchart for explaining the impedance matching method of the multiplexer according to the embodiment.
Description of the symbols
1, a multiplexer;
2 an antenna element;
a 2a terminal;
5a piezoelectric substrate;
10. 30 a transmission input terminal;
11. 13a transmission side filter;
12. 14 a receiving-side filter;
20. 40 receive the output terminal;
21 an inductance element (1 st inductance element, inductance element for filter matching);
31. 35 an inductance element (1 st circuit element);
32 capacitance elements (2 nd circuit elements);
33 an inductance element (2 nd circuit element);
34 a capacitive element (1 st circuit element);
50 a common terminal;
51 a high acoustic speed support substrate;
52 a low acoustic velocity membrane;
53 a piezoelectric film;
54. 101a, 101b IDT electrodes;
55 a protective layer;
61. 63 a transmission output terminal;
62. 64 receive an input terminal;
100 resonators;
102. 103, 104, 105, 201, 301, 302, 303, 304, 401, 402, 403, 404, 405 series resonators;
110a, 110b electrode fingers;
111a, 111b bus bar electrodes;
141. 363 inductance element (2 nd inductance element);
151. 152, 153, 154, 251, 252, 253, 351, 352, 353, 354, 451, 452, 453, 454 parallel resonators;
161. 162, 361, 362, 461 inductive elements;
203 a longitudinal coupling type filter unit;
211、212、213、214、215 IDT：
220. 221 a reflector;
230 input ports;
240 output port;
541 an adhesion layer;
542 a main electrode layer.
Detailed Description
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below are all illustrative or specific examples. The numerical values, shapes, materials, constituent elements, arrangement of constituent elements, connection modes, and the like shown in the following embodiments are merely examples, and do not limit the gist of the present invention. Among the components in the following embodiments, components not described in the independent claims will be described as optional components. The sizes of the components shown in the drawings and the ratio of the sizes are not necessarily strict.
(embodiment mode 1)
[1. basic Structure of multiplexer ]
In embodiment 1, the quadroplexers of Band25 (transmission pass Band: 1850-.
The multiplexer 1 according to the present embodiment is a quad multiplexer in which a Band25 duplexer and a Band66 duplexer are connected to each other via a common terminal 50.
Fig. 1 is a circuit configuration diagram of a multiplexer 1 according to the embodiment. As shown in the figure, the multiplexer 1 includes: transmission- side filters 11 and 13, reception- side filters 12 and 14, an inductance element 21, a common terminal 50, transmission input terminals 10 and30, and reception output terminals 20 and 40. The multiplexer 1 is connected to the antenna element 2 at the common terminal 50. The inductance element 31 is connected between a connection path between the common terminal 50 and the antenna element 2 and a ground line serving as a reference terminal. The capacitive element 32 is connected in series to a connection path between the common terminal 50 and the antenna element 2. The inductance element 31 is connected to the common terminal 50 side of the capacitance element 32.
In the present embodiment, the inductance element 31 corresponds to the 1 st circuit element, the capacitance element 32 corresponds to the 2 nd circuit element, and the inductance element 21 corresponds to the 1 st inductance element. The inductance element 31 and the capacitance element 32 may be included in the multiplexer 1, or may be externally attached to the multiplexer 1. The capacitive element 32 may be connected to the common terminal 50 side of the inductive element 31.
The transmission filter 11 is an unbalanced input/unbalanced output type Band pass filter (1 st elastic wave filter) that receives a transmission wave generated by a transmission circuit (RFIC, etc.) via a transmission input terminal 10, filters the transmission wave at the transmission pass Band (1850-.
The reception side filter 12 is an unbalanced-input/unbalanced-output type Band pass filter (2 nd elastic wave filter) which receives a reception wave input from the common terminal 50, filters the reception wave in a reception pass Band (1930-. Further, an inductance element 21 is connected in series between the reception filter 12 and the common terminal 50. The inductance element 21 is connected to the common terminal 50 side of the reception filter 12, and the impedances of the transmission filters 11 and 13 and the reception filter 14, which have a passband outside the passband of the reception filter 12, are inductive.
The transmission filter 13 is an unbalanced input/unbalanced output type Band pass filter (3 rd elastic wave filter) that receives a transmission wave generated by a transmission circuit (RFIC, etc.) via a transmission input terminal 30, filters the transmission wave in a transmission pass Band (1710- "1780 MHz: 3 rd pass Band) of Band66, and outputs the transmission wave to the common terminal 50.
The reception side filter 14 is an unbalanced-input/unbalanced-output type Band pass filter (4 th elastic wave filter) that receives a reception wave input from the common terminal 50, filters the reception wave in a reception pass Band (2010-2200 MHz: 4 th pass Band) of Band66, and outputs the reception wave to the reception output terminal 40.
The transmission filters 11 and 13 and the reception filter 14 are directly connected to the common terminal 50.
The inductance element 21 is not limited to the space between the reception filter 12 and the common terminal 50, and may be connected in series between the reception filter 14 and the common terminal 50.
[2. Structure of surface Acoustic wave resonator ]
Here, the structure of the surface acoustic wave resonators constituting the transmission- side filters 11 and 13 and the reception- side filters 12 and 14 will be described.
Fig. 2 is a schematic diagram schematically showing a resonator of a surface acoustic wave filter according to an embodiment, where (a) is a plan view and (b) and (c) are cross-sectional views taken along a one-dot chain line shown in (a). Fig. 2 is a schematic plan view and a schematic cross-sectional view illustrating the structure of the series resonators of the transmission side filter 11 among the plurality of resonators constituting the transmission side filters 11 and 13 and the reception side filters 12 and 14. The series resonator shown in fig. 2 is used to explain a typical structure of the plurality of resonators, and the number, length, and the like of electrode fingers constituting the electrodes are not limited thereto.
The resonator 100 constituting the transmission- side filters 11 and 13 and the reception- side filters 12 and 14 is composed of a piezoelectric substrate 5 and IDT (inter digital Transducer) electrodes 101a and 101b having a comb-like shape.
As shown in fig. 2 (a), a pair of IDT electrodes 101a and 101b facing each other are formed on the piezoelectric substrate 5. The IDT electrode 101a includes a plurality of electrode fingers 110a parallel to each other and a bus bar electrode 111a connecting the plurality of electrode fingers 110 a. The IDT electrode 101b includes a plurality of electrode fingers 110b parallel to each other and a bus bar electrode 111b connecting the plurality of electrode fingers 110 b. The plurality of electrode fingers 110a and 110b are formed along a direction orthogonal to the X-axis direction.
Further, the IDT electrode 54 including the plurality of electrode fingers 110a and 110b and the bus bar electrodes 111a and 111b has a laminated structure of the adhesion layer 541 and the main electrode layer 542 as shown in fig. 2 (b).
The adhesion layer 541 is a layer for improving adhesion between the piezoelectric substrate 5 and the main electrode layer 542, and Ti is used as a material, for example. The thickness of the adhesion layer 541 is, for example, 12 nm.
As the material of the main electrode layer 542, for example, a1 containing 1% Cu is used. The film thickness of the main electrode layer 542 is, for example, 162 nm.
The protective layer 55 is formed to cover the IDT electrodes 101a and 101 b. The protective layer 55 is a layer for protecting the main electrode layer 542 from the external environment, adjusting the frequency-temperature characteristics, improving the moisture resistance, and the like, and is a film mainly composed of, for example, silicon dioxide. The thickness of the protective layer 55 is, for example, 25 nm.
The materials constituting the adhesive layer 541, the main electrode layer 542, and the protective layer 55 are not limited to the above materials. Further, the IDT electrode 54 may not have the above-described laminated structure. The IDT electrode 54 may be made of a metal such as Ti, Al, Cu, Pt, Au, Ag, Pd, or an alloy, or may be made of a plurality of stacked bodies made of the above-described metal or alloy. Further, the protective layer 55 may not be formed.
Next, a laminated structure of the piezoelectric substrate 5 will be explained.
As shown in fig. 2 (c), the piezoelectric substrate 5 includes a high sound velocity support substrate 51, a low sound velocity film 52, and a piezoelectric film 53, and has a structure in which the high sound velocity support substrate 51, the low sound velocity film 52, and the piezoelectric film 53 are laminated in this order.
Piezoelectric film 53X-propagating LiTaO cut by 50 ° Y3Piezoelectric single crystal or piezoelectric ceramicLithium tantalate single crystal or ceramic cut on a plane whose normal is an axis rotated by 50 ° from the Y axis with the X axis as the center axis, is a single crystal or ceramic in which surface acoustic waves propagate in the X axis direction). The piezoelectric film 53 is, for example, 600nm thick. In addition, for the transmitting side filter 13 and the receiving side filter 14, the X propagation LiTaO cut by 42-45 degree Y is used3A piezoelectric film 53 made of a piezoelectric single crystal or a piezoelectric ceramic.
The high acoustic velocity support substrate 51 is a substrate that supports the low acoustic velocity film 52, the piezoelectric film 53, and the IDT electrode 54. The high acoustic velocity support substrate 51 is a substrate in which the acoustic velocity of a Bulk wave (Bulk wave) in the high acoustic velocity support substrate 51 is higher than the acoustic velocity of a surface wave or a boundary wave propagating through the piezoelectric film 53, and functions to confine the surface acoustic wave to a portion where the piezoelectric film 53 and the low acoustic velocity film 52 are laminated so as not to leak downward from the high acoustic velocity support substrate 51. The high sound velocity support substrate 51 is, for example, a silicon substrate and has a thickness of, for example, 200 μm.
The low acoustic velocity film 52 is a film in which the acoustic velocity of the bulk wave in the low acoustic velocity film 52 is lower than the acoustic wave propagating through the piezoelectric film 53, and is disposed between the piezoelectric film 53 and the high acoustic velocity support substrate 51. This structure and the property that the energy of the acoustic wave is concentrated essentially in a medium with a low acoustic velocity can suppress the leakage of the surface acoustic wave energy to the outside of the IDT electrode. The low acoustic velocity film 52 is a film mainly composed of, for example, silicon dioxide, and has a thickness of, for example, 670 nm.
According to the above-described laminated structure of the piezoelectric substrate 5, the Q value at the resonance frequency and the anti-resonance frequency can be significantly increased as compared with the conventional structure using a single piezoelectric substrate. That is, since a surface acoustic wave resonator having a high Q value can be configured, a filter having a small insertion loss can be configured using the surface acoustic wave resonator.
When the inductance element 21 for impedance matching is connected in series to the common terminal 50 of the reception filter 12, a circuit element such as an inductance element or a capacitance element is added to obtain impedance matching between the plurality of surface acoustic wave filters. Thus, the Q value of the resonator 100 is assumed to be equivalently small. However, even in such a case, the Q value of the resonator 100 can be maintained at a high value by the above-described laminated structure of the piezoelectric substrate 5. Therefore, a surface acoustic wave filter having low loss in a frequency band can be formed.
The high sound velocity support substrate 51 may have a structure in which a support substrate and a high sound velocity film that has a higher sound velocity of a bulk wave propagating than an elastic wave of a boundary wave or a surface wave propagating through the piezoelectric film 53 are laminated. In this case, as the support substrate, various ceramics such as sapphire, lithium tantalate, lithium niobate, quartz, alumina, magnesia, silicon nitride, aluminum nitride, silicon carbide, zirconia, cordierite, mullite, talc, forsterite, and the like, dielectrics such as glass, semiconductors such as silicon, gallium nitride, and the like, resin substrates, and the like can be used. As the high sound velocity film, various high sound velocity materials such as aluminum nitride, aluminum oxide, silicon carbide, silicon nitride, silicon oxynitride, a DLC film, diamond, a medium containing the above materials as a main component, and a medium containing a mixture of the above materials as a main component can be used.
In fig. 2 (a) and (b), λ represents the repetition pitch of the plurality of electrode fingers 110a and 110b constituting the IDT electrodes 101a and 101b, L represents the crossing width of the IDT electrodes 101a and 101b, W represents the width of the electrode fingers 110a and 110b, S represents the width between the electrode fingers 110a and 110b, and h represents the height of the IDT electrodes 101a and 101 b.
[3 ] Structure of each Filter and inductance element ]
[3-1. Circuit configuration of Transmission side Filter ]
Hereinafter, the circuit configuration of each filter will be described with reference to fig. 3A to 3D and 4.
Fig. 3A is a circuit configuration diagram of the transmission side filter 11 of the Band25 constituting the multiplexer 1 according to the embodiment. As shown in fig. 3A, the transmission filter 11 includes: series resonators 102 to 105, parallel resonators 151 to 154, and matching inductance elements 141, 161, and 162.
The series resonators 102-105 are connected in series between the transmission input terminal 10 and the transmission output terminal 61. The parallel resonators 151 to 154 are connected in parallel with each other between the reference terminal (ground line) and each connection point of the transmission input terminal 10, the transmission output terminal 61, and the series resonators 102 to 105. The transmission side filter 11 constitutes a ladder type band pass filter by the above-described connection structure of the series resonators 102 to 105 and the parallel resonators 151 to 154.
The inductance element 141 is connected in series between the transmission input terminal 10 and the series resonator 102 and between the transmission input terminal 10 and the parallel resonator 151. The inductance element 141 is a 2 nd inductance element, and the inductance element 141 is provided in series with the transmission side filter 11, which requires isolation of the reception side filter 12 to which the inductance element 21 described later is connected, at the transmission input terminal 10 on the opposite side of the common terminal 50 connected to the antenna element 2. The inductance element 141 may be connected between the reference terminal and a connection path between the transmission input terminal 10 and the series resonator 102. By providing the inductance element 141, the isolation of the transmission filter 11 can be increased by coupling the inductance element 141 to the other inductance elements 161 and 162.
The inductance element 161 is connected between the reference terminal and the connection point of the parallel resonators 152, 153, and 154. The inductance element 162 is connected between the parallel resonator 151 and the reference terminal.
The transmission output terminal 61 is connected to the common terminal 50 (see fig. 1). The transmission output terminal 61 is connected to the series resonator 105, and is not directly connected to any of the parallel resonators 151 to 154.
Fig. 3C is a circuit configuration diagram of the transmission side filter 13 of the Band66 constituting the multiplexer 1 according to the embodiment. As shown in fig. 3C, the transmission filter 13 includes: series resonators 301 to 304, parallel resonators 351 to 354, and matching inductance elements 361 to 363.
The series resonators 301 to 304 are connected in series with each other between the transmission input terminal 30 and the transmission output terminal 63. The parallel resonators 351 to 354 are connected in parallel with each other between the reference terminal (ground line) and each connection point of the transmission input terminal 30, the transmission output terminal 63, and the series resonators 301 to 304. The transmission side filter 13 constitutes a ladder type band pass filter by the above-described connection structure of the series resonators 301 to 304 and the parallel resonators 351 to 354. The inductance element 361 is connected between the reference terminal and the connection point of the parallel resonators 351 and 352. The inductance element 362 is connected between the parallel resonator 353 and the reference terminal. The inductance element 363 is connected between the transmission input terminal 30 and the series resonator 301. The inductor element 363 is a 2 nd inductor element, similarly to the inductor element 141 in the transmission filter 11 described above. The inductance element 363 may be connected between the reference terminal and the connection path of the transmission input terminal 30 and the series resonator 301.
The transmission output terminal 63 is connected to the common terminal 50 (see fig. 1). The transmission output terminal 63 is connected to the series resonator 304, and is not directly connected to any of the parallel resonators 351 to 354.
For example, PA (not shown) is connected to the transmission input terminals 10 and 30. The characteristic impedance of the transmission input terminals 10 and30 may also be different depending on the characteristics of the PA to be connected.
[3-2. Circuit configuration of reception side Filter ]
Fig. 3B is a circuit configuration diagram of the reception side filter 12 of the Band25 constituting the multiplexer 1 according to the embodiment. As shown in fig. 3B, the reception filter 12 includes, for example, a longitudinally coupled surface acoustic wave filter section. More specifically, the reception-side filter 12 includes: longitudinal coupling filter section 203, series resonator 201, and parallel resonators 251 to 253.
Fig. 4 is a schematic plan view showing an electrode structure of the longitudinal coupling filter section 203 according to the embodiment. As shown in the figure, the longitudinal coupling filter section 203 includes: IDTs 211 to 215, reflectors 220 and 221, an input port 230, and an output port 240.
The IDTs 211-215 are each formed by a pair of IDT electrodes facing each other. The IDTs 212 and 214 are disposed so as to sandwich the IDT213 in the X-axis direction, and the IDTs 211 and 215 are disposed so as to sandwich the IDTs 212 to 214 in the X-axis direction. Reflectors 220 and 221 are disposed so as to sandwich IDTs 211 to 215 in the X-axis direction. Further, IDTs 211, 213 and 215 are connected in parallel between the input port 230 and the reference terminal (ground line), and IDTs 212 and 214 are connected in parallel between the output port 240 and the reference terminal.
As shown in fig. 3B, the series resonator 201 and the parallel resonators 251 and 252 constitute a ladder filter unit.
The reception input terminal 62 is connected to the common terminal 50 (see fig. 1) via the inductance element 21 (see fig. 1). Further, as shown in fig. 3B, the reception input terminal 62 is connected to the parallel resonator 251.
Fig. 3D is a circuit configuration diagram of the reception side filter 14 of the Band66 constituting the multiplexer 1 according to the embodiment. As shown in fig. 3D, the reception filter 14 includes: series resonators 401 to 405, parallel resonators 451 to 454, and matching inductance element 461.
The series resonators 401 to 405 are connected in series with each other between the reception output terminal 40 and the reception input terminal 64. The parallel resonators 451 to 454 are connected in parallel with each other between the reference terminal (ground line) and each connection point of the reception output terminal 40, the reception input terminal 64, and the series resonators 401 to 405. The receiving side filter 14 forms a ladder type band pass filter by the above-described connection structure of the series resonators 401 to 405 and the parallel resonators 451 to 454. The inductance element 461 is connected between the reference terminal and the connection point of the parallel resonators 451, 452, and 453.
The reception input terminal 64 is connected to the common terminal 50 (see fig. 1). As shown in fig. 3D, the reception input terminal 64 is connected to the series resonator 405, but not directly connected to the parallel resonator 454.
For example, LNAs (not shown) are connected to the reception output terminals 20 and 40. The characteristic impedance of the receive output terminals 20 and 40 may also differ depending on the characteristics of the connected LNA. The characteristic impedances of the reception output terminals 20 and 40 and the transmission input terminals 10 and30 may be different from each other.
The arrangement of the resonators and circuit elements in the surface acoustic wave filter provided in the multiplexer 1 according to the present embodiment is not limited to the arrangement exemplified in the transmission side filters 11 and 13 and the reception side filters 12 and 14 according to the above-described embodiments. The arrangement of the resonators and circuit elements in the surface acoustic wave filter described above differs depending on the required specification of the pass characteristic in each frequency Band (Band). The arrangement structure refers to, for example, the number of series resonators and parallel resonators arranged, and also refers to selection of a filter structure such as a ladder type or a longitudinal coupling type.
In the arrangement structure of the resonators and circuit elements in the elastic wave filter provided in the multiplexer 1 according to the present embodiment, the main features of the present invention are (1) that the transmission- side filters 11 and 13 and the reception- side filters 12 and 14 are each provided with at least one of a series resonator and a parallel resonator, (2) that the reception input terminal 62 of the reception-side filter 12 as one elastic wave filter is connected to the common terminal 50 via the inductance element 21, and connected to the parallel resonator 251, (3) the transmission output terminals 61 and 63 of the transmission filters 11 and 13 and the reception input terminal 64 of the reception filter 14, which are elastic wave filters other than the reception filter 12, are connected to the common terminal 50, and is connected to the series resonators 105, 304, and 405 among the series resonators and the parallel resonators.
That is, the multiplexer 1 according to the embodiment includes: a plurality of surface acoustic wave filters having passbands different from each other; a common terminal 50 in which an inductance element 31 is connected between a connection path to the antenna element 2 and a reference terminal, and a capacitance element 32 is connected in series to the connection path to the antenna element 2; and an inductance element 21 connected in series between the common terminal 50 and the reception input terminal 62 of the reception side filter 12 as one elastic wave filter.
Here, each of the plurality of surface acoustic wave filters includes: at least one of a series resonator having an IDT electrode formed on the piezoelectric substrate 5 (see fig. 2) and connected between the input terminal and the output terminal, and a parallel resonator having an IDT electrode formed on the piezoelectric substrate 5 and connected between a connection path connecting the input terminal and the output terminal and the reference terminal. Further, among the plurality of surface acoustic wave filters, the reception input terminal 62 of the reception side filter 12 is connected to the common terminal 50 via the inductance element 21 and is connected to the parallel resonator 251. On the other hand, the transmission output terminals 61 and 63 and the reception input terminal 64 of the transmission side filters 11 and 13 and the reception side filter 14 are connected to the common terminal 50, the series resonators 105, 304, and 405, and are not connected to the parallel resonators.
Further, the inductance element 31 is connected between the reference terminal and the connection path of the common terminal 50 and the antenna element 2, and the capacitance element 32 is connected in series to the connection path of the common terminal 50 and the antenna element 2. By changing the inductance value of the inductance element 31 and the capacitance value of the capacitance element 32, the complex impedance of the multiplexer 1 viewed from the common terminal 50 can be adjusted so as to move in 2 directions of the capacitive side or the inductive side, and the open side or the short side in the smith chart.
[4. operation principle of surface acoustic wave filter ]
Here, the operation principle of the ladder type surface acoustic wave filter according to the present embodiment will be described.
For example, the parallel resonators 151 to 154 shown in fig. 3A have a resonance frequency frp and an anti-resonance frequency fap (> frp) in the resonance characteristics, respectively. The series resonators 102 to 105 have a resonance frequency frs and an anti-resonance frequency fas (> frs > frp) in the resonance characteristics, respectively. The resonance frequencies frs of the series resonators 102-105 are designed to be substantially uniform, but need not be uniform. The anti-resonance frequencies fas of the series resonators 102 to 105, the resonance frequencies frp of the parallel resonators 151 to 154, and the anti-resonance frequencies fap of the parallel resonators 151 to 154 are the same, and do not necessarily coincide with each other.
When a band-pass filter is configured by ladder-type resonators, the anti-resonance frequency fap of the parallel resonators 151 to 154 is made close to the resonance frequency frs of the series resonators 102 to 105. Thus, the impedance of the parallel resonators 151 to 154 is close to 0 and is a low-frequency side stop band in the vicinity of the resonance frequency frp. When the frequency increases from this point, the impedances of the parallel resonators 151 to 154 become high in the vicinity of the anti-resonance frequency fap, and the impedances of the series resonators 102 to 105 become close to 0 in the vicinity of the resonance frequency frs. Thus, the signal pass band is formed in the signal path from the transmission input terminal 10 to the transmission output terminal 61 in the vicinity of the anti-resonance frequency fap to the resonance frequency frs. Further, when the frequency becomes high and becomes near the anti-resonance frequency fas, the impedances of the series resonators 102 to 105 become high, and the high-frequency side stop band is formed. That is, the steepness of the attenuation characteristic in the high-frequency side stop band is greatly influenced depending on where the anti-resonance frequency fas of the series resonators 102 to 105 is set outside the signal pass band.
When a high-frequency signal is input from the transmission/input terminal 10 to the transmission filter 11, a potential difference is generated between the transmission/input terminal 10 and the reference terminal, and the piezoelectric substrate 5 is deformed, thereby generating a surface acoustic wave propagating in the X direction. Here, the pitch λ of the IDT electrodes 101a and 101b is made substantially equal to the wavelength of the passband, and only a high-frequency signal having a frequency component desired to be passed is passed through the transmission filter 11.
Hereinafter, the high-frequency transmission characteristics and impedance characteristics of the multiplexer 1 according to the present embodiment will be described while comparing them with those of the multiplexer according to the comparative example.
[5. high-frequency transmission characteristics of multiplexer ]
Hereinafter, the high-frequency transmission characteristic of the multiplexer 1 according to the present embodiment will be described while being compared with the high-frequency transmission characteristic of the multiplexer according to the comparative example.
The multiplexer according to the comparative example has the following structure: in comparison with the multiplexer 1 according to the present embodiment shown in fig. 1, the inductance element 31 is not connected between the connection path between the common terminal 50 and the antenna element 2 and the ground line as the reference terminal, and the capacitance element 32 is not formed in series in this connection path. The multiplexer according to the comparative example is configured such that an inductance element is connected in series between the common terminal 50 and the antenna element 2.
Fig. 5A is a graph comparing the pass characteristics of transmission side filter 11 of Band25 according to the embodiment and the comparative example. Fig. 5B is a graph comparing the pass characteristics of receiving side filter 12 of Band25 according to the embodiment and the comparative example. Fig. 5C is a graph comparing the pass characteristics of transmitting side filter 13 of Band66 according to the embodiment and the comparative example. Fig. 5D is a graph comparing the pass characteristics of receiving side filter 14 of Band66 according to the embodiment and the comparative example.
As is apparent from fig. 5A to 5D, the insertion loss in the pass Band of the multiplexer 1 according to the present embodiment is more excellent on the transmission side and the reception side of the Band25 and on the transmission side and the reception side of the Band66 than on the pass Band of the multiplexer according to the comparative example. Further, it is understood that the multiplexer 1 according to the embodiment satisfies the required specifications (transmission-side insertion loss of 2.0dB or less and reception-side insertion loss of 3.0dB or less) in the pass Band in all the bands on the transmission side and the reception side of the Band25 and on the reception side of the Band 66.
On the other hand, it is understood that the multiplexer according to the comparative example does not satisfy the required specification in the pass Band on the transmitting side and the receiving side of the Band 25.
As described above, according to the multiplexer 1 of the present embodiment, even if the number of frequency bands and the number of modes to be handled are increased, the insertion loss in the pass band of each filter constituting them can be reduced.
Hereinafter, impedance matching in the multiplexer 1 according to the present embodiment will be described including the reason why the multiplexer 1 can achieve low loss in the pass band.
[6. impedance matching in multiplexer ]
Fig. 6A and 6B are smith charts showing the complex impedance observed from the transmission output terminal 61 of the transmission filter 11 alone and the complex impedance observed from the reception input terminal 62 of the reception filter 12 alone in Band25 according to the embodiment. Fig. 6C and 6D are smith charts showing the complex impedance seen from the transmission output terminal 63 of the Band66 alone in the embodiment and the complex impedance seen from the reception input terminal 64 of the reception filter 14 alone, respectively.
In the multiplexer 1 according to the embodiment, the impedance characteristics of the transmission side filters 11 and 13 and the reception side filter 14 are independent of each otherDesigned as a complex impedance in the frequency domain outside the pass band to the open side. Specifically, the region B outside the pass band of the transmission side filter 11 to which the inductance element 21 is not connected in fig. 6AOUT11And an out-of-band region B of the transmission side filter 13 to which no inductance element 21 is connected in FIG. 6COUT13And the region B outside the pass band of the reception side filter 14 to which no inductance element 21 is connected in FIG. 6DOUT14The complex impedance of (2) is arranged substantially on the open circuit side. In order to realize these complex impedance arrangements, the resonators connected to the common terminal 50 of the above-mentioned 3 filters are series resonators, not parallel resonators.
On the other hand, in the reception side filter 12 to which the inductance element 21 is connected, the resonators connected to the common terminal 50 are parallel resonators. Thus, as shown in fig. 6B, the region B outside the pass band of the reception side filter 12OUT12Is arranged on the substantially short-circuit side. About the region B outside the pass bandOUT12The purpose of being arranged on the short-circuit side will be described later.
Fig. 7 is a smith chart (left side) showing the complex impedance observed from the common terminal 50 of the circuit cell in which all the filters other than the reception side filter 12 of Band25 according to the embodiment are connected in parallel via the common terminal 50, and a smith chart (right side) showing the complex impedance observed from the common terminal 50 of the circuit cell in which the reception side filter 12 of Band25 according to the embodiment and the inductance element 21 are connected in series.
As shown in fig. 7, the complex impedance in the predetermined passband when the single receiving filter 12 is viewed through the inductance element 21 in the state where the inductance element 21 and the input terminal of the receiving filter 12 are connected in series, and the complex impedance in the predetermined passband when the transmitting filters 11 and 13 and the receiving filter 14 are viewed from the terminal side connected to the common terminal 50 in the state where one of the input terminal and the output terminal of the transmitting filters 11 and 13 and the receiving filter 14 close to the antenna element 2 is connected to the common terminal 50, are substantially close to complex conjugates. That is, when the 2 complex impedances are combined, impedance matching is achieved, and the complex impedance of the combined circuit comes near the characteristic impedance.
The complex impedances of the 2 circuits are in a complex conjugate relationship, and include a relationship in which the positive and negative of the complex components of the complex impedances are inverted, and are not limited to a case in which the absolute values of the complex components are equal. That is, the complex conjugate relationship in the present embodiment includes a relationship in which the complex impedance of one circuit is capacitive (lower half circle of the smith chart) and the complex impedance of the other circuit is inductive (upper half circle of the smith chart).
Here, as shown in fig. 6B, the region B outside the pass band of the reception side filter 12 is setOUT12The purpose of the complex impedance of (2) is to make the outside-passband region B by the inductance element 21 substantially short-circuitedOUT12The complex impedance (the pass band of the transmission side filters 11 and 13 and the reception side filter 14) is shifted to a position having the complex conjugate relationship. The inductance value of the inductor element 21 at this time is, for example, 5.9 nH.
It is assumed that the region B outside the pass band of the filter 12 on the reception sideOUT12In the case of the open side, the outside-passband region B must be made by the inductance element 21 having a larger inductance valueOUT12And moved to a position having the complex conjugate relationship described above. Since the inductance element 21 is connected in series with the reception filter 12, the insertion loss in the passband of the reception filter 12 is deteriorated as the inductance value is larger. Therefore, as in the reception side filter 12 according to the embodiment, the parallel resonator 251 is used to form the out-of-band region BOUT12The complex impedance of (2) is arranged on the short-circuit side, so that the inductance value of the inductance element 21 can be reduced, and thus the insertion loss in the pass band can be reduced.
Fig. 8A is a smith chart showing the complex impedance of the multiplexer 1 according to the embodiment as viewed from the common terminal 50. That is, the complex impedance shown in fig. 8A represents the complex impedance observed from the common terminal 50 of the multiplexer in which the 2 circuits shown in fig. 7 are combined. Impedance matching can be achieved by configuring the complex impedances of the 2 circuits shown in fig. 7 in a complex conjugate relationship with each other so that the complex impedance of the synthesized circuit approaches the characteristic impedance in 4 pass bands.
Fig. 8B is a smith chart showing the complex impedance seen from the antenna element 2 side in the case where the inductive element 31 is connected between the reference terminal and the connection path between the common terminal 50 and the antenna element 2 of the multiplexer 1 according to the embodiment, and the capacitive element 32 is connected in series to the connection path between the common terminal 50 and the antenna element 2. As shown in fig. 8A, in a circuit in which 2 circuits arranged in a complex conjugate relationship with each other are combined, the complex impedance deviates from the characteristic impedance to the capacitive side and the open side.
In contrast, the complex impedance of the multiplexer 1 viewed from the common terminal 50 is adjusted to the inductive side and the short-circuited side by connecting the inductive element 31 between the reference terminal and the connection path between the common terminal 50 and the antenna element 2 and connecting the capacitive element 32 in series to the connection path between the common terminal 50 and the antenna element 2. In this case, the inductance value of the inductance element 31 is, for example, 7.0nH, and the capacitance value of the capacitance element 32 is 2.5 pF.
Accordingly, in the transmission- side filters 11 and 13 and the reception- side filters 12 and 14, the characteristic impedance of the terminal on the opposite side from the antenna element 2, out of the input terminal and the output terminal, can be adjusted in accordance with the PA and the LNA which are connected. Therefore, impedance matching at the antenna terminal can be easily achieved without complicating the design of the transmission side filters 11 and 13 and the reception side filters 12 and 14.
[7. summary ]
As described above, the multiplexer 1 according to the embodiment (1) connects the inductance element 21 in series between the reception filter 12 and the common terminal 50, (2) connects the inductance element 31 between the reference terminal and the connection path between the common terminal 50 and the antenna element 2, and connects the capacitance element 32 in series between the common terminal 50 and the connection path of the antenna element 2, (3) connects the parallel resonator 251 to the reception input terminal 62 of the reception filter 12, and (4) connects the series resonators 105, 304, and 405 to the transmission output terminal 61 of the transmission filter 11, the transmission output terminal 63 of the transmission filter 13, and the reception input terminal 64 of the reception filter 14, respectively.
This makes it possible to set the complex impedance observed from the common terminal 50 of the circuit unit in which the inductance element 21 and the reception filter 12 are connected in series, and the complex impedance observed from the common terminal 50 of the circuit unit in which all the filters other than the reception filter 12 are connected in parallel via the common terminal 50, to a complex conjugate relationship. This makes it possible to easily match the complex impedance observed from the common terminal 50 of the multiplexer 1 having the circuit in which the 2 circuits are combined with the characteristic impedance while securing a low loss in the pass band. Further, by connecting the inductance element 31 between the reference terminal and the connection path between the common terminal 50 and the antenna element 2 and connecting the capacitance element 32 in series to the connection path between the common terminal 50 and the antenna element 2, the complex impedance viewed from the common terminal 50 of the multiplexer 1 can be moved in 2 directions on the smith chart. For example, as described above, the complex impedance viewed from the common terminal 50 of the multiplexer 1 can be adjusted to the inductive side and the short-circuit side. Therefore, impedance matching at the antenna terminal can be easily achieved without complicating the design of the transmission side filters 11 and 13 and the reception side filters 12 and 14.
In addition, the present embodiment shows the following configuration: while the inductance element 31 is connected in series between the reference terminal and the connection path between the common terminal 50 and the antenna element 2, and the capacitance element 32 is connected in series between the common terminal 50 and the connection path of the antenna element 2, the inductance element and the capacitance element may be combined arbitrarily with each other as a circuit element connected between the reference terminal and the connection path between the common terminal 50 and the antenna element 2, and a circuit element connected in series between the common terminal 50 and the connection path of the antenna element 2. In addition, at least one circuit element connected between the reference terminal and the connection path between the common terminal 50 and the antenna element 2, and at least 2 circuit elements connected in series to the connection path between the common terminal 50 and the antenna element 2 may be provided.
(embodiment mode 2)
The multiplexer 1 according to embodiment 2 differs from the multiplexer 1 shown in embodiment 1 in the type and connection position of the circuit element connected between the common terminal 50 and the antenna element 2.
Fig. 9 is a circuit configuration diagram showing an example of the multiplexer 1 according to the present embodiment. In the multiplexer 1 shown in fig. 9, the inductance element 33 is connected in series to a connection path between the common terminal 50 and the antenna element 2, and the capacitance element 34 is connected between a reference terminal and a connection path between the common terminal 50 and the antenna element 2. The inductance element 33 is connected to the common terminal 50 side of the capacitance element 34.
Here, the optimum combination of the types and connection positions of the elements connected between the common terminal 50 and the antenna element 2 will be described. Fig. 10 is a diagram for explaining the relationship between the complex impedance seen from the common terminal 50 and the types and connection positions of the circuit elements connected between the common terminal 50 and the antenna element 2 in the multiplexer 1 according to the present embodiment. Fig. 11A to 11D are diagrams showing examples of the types and connection positions of circuit elements connected between the common terminal and the antenna element in the multiplexer according to the present embodiment. In fig. 11A to 11D, the connection terminal of the antenna element 2 is shown as a terminal 2 a.
The optimum combination of the types and connection positions of the circuit elements connected between the common terminal 50 and the terminal 2a of the antenna element 2 differs depending on the value of the real part of the characteristic impedance of the multiplexer 1 as viewed from the common terminal 50 and on which quadrant the characteristic impedance in the high-frequency pass band of the multiplexer 1 is located on the smith chart.
When the real part of the characteristic impedance of the multiplexer 1 is 50 Ω or more, the combination of the inductance element 33 and the capacitance element 34 shown in fig. 11A is effective even when the characteristic impedance in the pass band of the multiplexer 1 is in any of the 3 rd quadrant and the 4 th quadrant in the smith chart shown in fig. 10. That is, as shown in fig. 11A, the following structure is adopted: an inductance element 33 is connected in series to a connection path between a common terminal 50 (see fig. 9) and a terminal 2a of the multiplexer 1, and a capacitance element 34 is connected between a reference terminal and a connection path between the inductance element 33 and the common terminal 50.
With this configuration, the complex impedance of the multiplexer viewed from the common terminal can be matched with the characteristic impedance while ensuring low loss in the pass band.
In addition, when the real part of the characteristic impedance of the multiplexer 1 is smaller than 50 Ω and the characteristic impedance of the high-frequency pass band of the multiplexer 1 is in quadrant 3 in the smith chart shown in fig. 10, the combination of the inductance element 33 and the capacitance element 34 shown in fig. 11B is effective.
That is, as shown in fig. 11B, the following structure is provided: the inductance element 33 is connected in series to a connection path between the common terminal 50 (see fig. 9) of the multiplexer 1 and the terminal 2a, and the capacitance element 34 is connected between the reference terminal and the connection path between the terminal 2a and the inductance element 33. The structure is the same as the combination of circuit elements shown in fig. 9.
Therefore, the combination of the inductance element 33 and the capacitance element 34 and the connection position shown in fig. 9 are effective in the case where the real part of the characteristic impedance viewed from the common terminal 50 side of the multiplexer 1 is less than 50 Ω and the characteristic impedance in the pass band of the multiplexer 1 is in quadrant 3 in the smith chart.
In addition, when the real part of the characteristic impedance of the multiplexer 1 is smaller than 50 Ω and the characteristic impedance of the high-frequency pass band of the multiplexer 1 is in quadrant 4 in the smith chart shown in fig. 10, the combination of the inductance element 31 and the capacitance element 32 shown in fig. 11C and the combination of the inductance elements 31 and 33 shown in fig. 11D are effective.
That is, as shown in fig. 11C, the following structure is adopted: the capacitive element 32 is connected in series to a connection path between the common terminal 50 (see fig. 9) and the terminal 2a of the multiplexer 1, and the inductive element 31 is connected between the reference terminal and a connection path between the common terminal 50 and the capacitive element 32. This structure is the same as the combination of the inductance element 31 and the capacitance element 32 shown in fig. 1. Therefore, the combination of the inductance element 31 and the capacitance element 32 and the connection position shown in fig. 1 are effective in the case where the real part of the characteristic impedance viewed from the common terminal 50 side of the multiplexer 1 is less than 50 Ω and the characteristic impedance in the pass band of the multiplexer 1 is in quadrant 4 in the smith chart.
As shown in fig. 11D, the following configuration may be adopted: the inductance element 33 is connected in series to a connection path between the common terminal 50 (see fig. 9) and the terminal 2a of the multiplexer 1, and the inductance element 31 is connected between the reference terminal and a connection path between the common terminal 50 and the inductance element 33. With this configuration, it is also effective in the case where the real part of the characteristic impedance viewed from the common terminal 50 side of the multiplexer 1 is smaller than 50 Ω, and the characteristic impedance in the pass band of the multiplexer 1 is in the 4 th quadrant in the smith chart.
The number of circuit elements connected between the reference terminal and the connection path between the common terminal 50 and the antenna element 2, and the number of circuit elements connected in series between the reference terminal and the connection path between the common terminal 50 and the antenna element 2 are not limited to one, and may be 2 or more. Fig. 12 is a circuit configuration diagram showing another example of the multiplexer according to the present embodiment.
The multiplexer 1 shown in fig. 12 includes a capacitive element 32 in series in a connection path between the common terminal 50 and the antenna element 2. Further, an inductance element 31 is provided between a reference terminal and a connection path between the common terminal 50 and the capacitance element 32. Further, the multiplexer 1 shown in fig. 12 includes an inductance element 35 between a reference terminal and a connection path between the capacitance element 32 and the antenna element 2.
According to this configuration, since the 2 inductance elements 31 and 35 are respectively arranged between the reference terminal and the connection path between the common terminal 50 and the antenna element 2, further fine adjustment can be achieved. Therefore, impedance matching can be achieved by easily adjusting the characteristic impedance to the inductive side and the short-circuit side in the smith chart.
(other modifications, etc.)
While the multiplexer according to the embodiment of the present invention has been described above with reference to the embodiment of the quadplexer, the present invention is not limited to the above embodiment. For example, the following modifications can be made to the above embodiment.
For example, the piezoelectric film 53 of the piezoelectric substrate 5 according to the embodiment uses 50 ° Y-cut X-propagation LiTaO3Single crystal, butThe cut angle of the single crystal material is not limited thereto. That is, the present invention is not limited to: mixing LiTaO3The substrate is used as a piezoelectric substrate, and the cut angle of the piezoelectric substrate constituting the surface acoustic wave filter of the multiplexer according to the embodiment is 50 ° Y. Even if LiTaO having a cut angle other than the above is used3The surface acoustic wave filter of the piezoelectric substrate can also exhibit the same effect.
The multiplexer 1 according to the present invention may further have the following configuration: at least one 1 st circuit element is connected between a connection path of the antenna element 2 and the common terminal 50 and the reference terminal, and at least one 2 nd circuit element is connected in series to the connection path of the antenna element 2 and the common terminal 50. Here, the 1 st circuit element and the 2 nd circuit element may be an inductance element or a capacitance element, respectively. For example, the multiplexer 1 according to the present invention may have the following configuration: on the high-frequency substrate, a plurality of elastic wave filters having the above-described characteristics, and the 1 st inductance element, the 1 st circuit element, and the 2 nd circuit element on the chip are mounted.
The inductance element may be a chip inductor, for example, or may be formed of a conductor pattern of a high-frequency substrate. The capacitive element may be a chip capacitor, for example, or may be formed of a conductor pattern of a high-frequency substrate.
The multiplexer according to the present invention is not limited to the quad multiplexer of Band25+ Band66 as in the embodiment.
Fig. 13A is a diagram showing a configuration of a multiplexer according to modification 1 of the embodiment. For example, as shown in fig. 13A, the multiplexer according to the present invention may be a 6-Band duplexer applied to a system configuration in which Band25, Band4, and Band30 having a transmission Band and a reception Band are combined. In this case, for example, the inductance element 21 is connected in series to the reception side filter of Band25, and the parallel resonator is connected to the reception input terminal of the reception side filter of Band 25. Further, the series resonators are connected to the terminals of the 5 filters other than the reception side filter of Band25, which are connected to the common terminal, and the parallel resonators are not connected. Further, a capacitive element 32 is connected in series to a connection path between the common terminal and the antenna element 2, and an inductive element 31 is connected between the reference terminal and the connection path between the common terminal and the capacitive element 32.
Fig. 13B is a diagram showing a configuration of a multiplexer according to modification 2 of the embodiment. For example, as shown in fig. 13B, the multiplexer according to the present invention may be a 6-Band duplexer applied to a system configuration in which Band1, Band3, and Band7 having a transmission Band and a reception Band are combined. In this case, for example, the inductance element 21 is connected in series to the reception side filter of Band1, and the parallel resonator is connected to the reception input terminal of the reception side filter of Band 1. Further, the series resonators are connected to the terminals of the 5 filters other than the reception side filter of Band1, which are connected to the common terminal, and the parallel resonators are not connected. Further, a capacitive element 32 is connected in series to a connection path between the common terminal and the antenna element 2, and an inductive element 31 is connected between the reference terminal and the connection path between the common terminal and the capacitive element 32.
As described above, in the multiplexer according to the present invention, even when the characteristic impedance is different between the transmission terminal or the reception terminal side of the surface acoustic wave filter and the antenna terminal side, the impedance can be sufficiently matched to each terminal. This reduces the insertion loss in the pass band even when the number of elastic wave filters as components is large.
Further, the multiplexer according to the present invention may not have a configuration including a plurality of duplexers for performing transmission and reception. For example, the present invention can be applied to a transmission device having a plurality of transmission bands. That is, a transmission device may be a transmission device that receives a plurality of high-frequency signals having mutually different carrier frequency bands, filters the plurality of high-frequency signals, and wirelessly transmits the filtered high-frequency signals from a common antenna element, the transmission device including: a plurality of transmitting elastic wave filters for receiving a plurality of high frequency signals from the transmitting circuit and passing only a predetermined frequency band; and a common terminal to which at least one 1 st circuit element is connected between a connection path with the antenna element and the reference terminal, and to which at least one 2 nd circuit element is connected in series in the connection path with the antenna element. Here, each of the plurality of transmitting elastic wave filters includes: at least one of a series resonator having an IDT electrode formed on the piezoelectric substrate and connected between the input terminal and the output terminal, and a parallel resonator having an IDT electrode formed on the piezoelectric substrate and connected between a connection path connecting the input terminal and the output terminal and the reference terminal. Further, the output terminal of one of the plurality of transmission elastic wave filters is connected to the common terminal via an inductance element connected to the output terminal and the common terminal, and is connected to the parallel resonator. On the other hand, the output terminal of the transmission elastic wave filter other than the one transmission elastic wave filter is connected to the common terminal and to the series resonator out of the series resonators and the parallel resonators. The 1 st circuit element and the 2 nd circuit element may be inductive elements or capacitive elements.
Further, the multiplexer according to the present invention can be applied to, for example, a receiving apparatus having a plurality of reception bands. That is, a receiving apparatus may be a receiving apparatus that receives a plurality of high-frequency signals having mutually different carrier frequency bands via an antenna element, and that demultiplexes and outputs the plurality of high-frequency signals to a receiving circuit, the receiving apparatus including: a plurality of reception elastic wave filters for receiving a plurality of high-frequency signals from the antenna element and passing only a predetermined frequency band; and a common terminal to which at least one 1 st circuit element is connected between a connection path with the antenna element and the reference terminal, and to which at least one 2 nd circuit element is connected in series in the connection path with the antenna element. Here, each of the plurality of reception elastic wave filters includes: at least one of a series resonator having an IDT electrode formed on the piezoelectric substrate and connected between the input terminal and the output terminal, and a parallel resonator having an IDT electrode formed on the piezoelectric substrate and connected between a connection path connecting the input terminal and the output terminal and the reference terminal. Further, among the plurality of reception elastic wave filters, the input terminal of one reception elastic wave filter is connected to the common terminal via an inductance element connected to the input terminal and the common terminal, and is connected to the parallel resonator. On the other hand, the input terminal of the reception elastic wave filter other than the one reception elastic wave filter is connected to the common terminal and to the series resonator out of the series resonators and the parallel resonators. The 1 st circuit element and the 2 nd circuit element may be inductive elements or capacitive elements.
Even a transmitting device or a receiving device having the above-described configuration can exhibit the same effects as those of the multiplexer 1 according to the present embodiment.
The present invention is not limited to the multiplexer, the transmission device, and the reception device including the characteristic elastic wave filter and the inductance element as described above, but is also applicable to an impedance matching method for a multiplexer including such characteristic components as steps.
Fig. 14 is an operation flowchart for explaining the impedance matching method of the multiplexer according to the embodiment.
The impedance matching method of the multiplexer according to the present invention includes: (1) a step (S10) of adjusting a plurality of elastic wave filters such that, among a plurality of elastic wave filters having different pass bands, the complex impedance in the pass band of the other elastic wave filter when one elastic wave filter alone is viewed from one of the input terminal and the output terminal of the elastic wave filter (elastic wave filter A) is in a short-circuited state, and the complex impedance in the pass band of the other elastic wave filter when the elastic wave filter alone is viewed from one of the input terminal and the output terminal of the elastic wave filter (elastic wave filter B) other than the one elastic wave filter is in an open-circuited state; (2) a step (S20) of adjusting the inductance value of the filter-matching inductance element so that the complex impedance when the one elastic wave filter (elastic wave filter A) is connected in series with the filter-matching inductance element and when the one elastic wave filter is viewed from the filter-matching inductance element side and the complex impedance when another elastic wave filter (elastic wave filters B) other than the one elastic wave filter is connected in parallel with the common terminal and when the other elastic wave filter is viewed from the common terminal side are in a complex conjugate relationship; and (3) a step (S30) of adjusting at least one 1 st circuit element connected between the reference terminal and a connection path between the antenna element and the common terminal and at least one 2 nd circuit element connected in series to the connection path between the antenna element and the common terminal so that a complex impedance seen from the common terminal of a composite circuit in which the one elastic wave filter (elastic wave filter a) is connected to the common terminal via the filter matching inductance element and the other elastic wave filters (elastic wave filters B) are connected in parallel to the common terminal matches the characteristic impedance.
Here, the 1 st circuit element and the 2 nd circuit element are, for example, an antenna matching inductance element or an antenna matching capacitance element, respectively. In this case, the adjustment of the 1 st circuit element and the 2 nd circuit element may be performed by adjusting an inductance value of the antenna matching inductance element and a capacitance value of the antenna matching capacitance element. Further, the adjustment of the 1 st circuit element and the 2 nd circuit element may include changing the type, characteristics, connection position, combination, and the like of the 1 st circuit element and the 2 nd circuit element.
Further, (4) in the step of adjusting the plurality of elastic wave filters, of the plurality of elastic wave filters having at least one of a series resonator and a parallel resonator, in one of the elastic wave filters, the parallel resonator and the series resonator are disposed such that the parallel resonator is connected to the filter matching inductance element, and in the other elastic wave filter, the parallel resonator and the series resonator are disposed such that the series resonator of the parallel resonator and the series resonator is connected to the common terminal, wherein the series resonator has an IDT electrode formed on the piezoelectric substrate and is connected between the input terminal and the output terminal, and the parallel resonator has an IDT electrode formed on the piezoelectric substrate and is connected between a connection path connecting the input terminal and the output terminal and the reference terminal.
In this configuration, the degree of freedom of impedance matching can be improved by adjusting the 1 st circuit element and the 2 nd circuit element as described above. Thus, even when the characteristic impedance is different between the transmission terminal or the reception terminal side and the antenna terminal side of the surface acoustic wave filter, the impedance can be sufficiently matched to each terminal.
In the above-described embodiments, a surface acoustic wave filter having IDT electrodes is exemplified as a transmission-side filter and a reception-side filter constituting a multiplexer, a quadrupler, a transmission device, and a reception device. However, each of the filters constituting the multiplexer, the quadrupler, the transmitter, and the receiver according to the present invention may be an elastic Wave filter using a Boundary Acoustic Wave (BAW) or a Bulk Acoustic Wave (Bulk Acoustic Wave) including a series resonator and a parallel resonator. This also achieves the same effects as those of the multiplexer, the quadplexer, the transmission device, and the reception device according to the above embodiments.
In the multiplexer 1 according to the above-described embodiment, the configuration in which the inductive element 21 is connected in series to the reception-side filter 12 is exemplified, but the configuration in which the inductive element 21 is connected in series to the transmission- side filter 11 or 13 or the reception-side filter 14 is also included in the present invention. That is, the multiplexer according to the present invention may have a configuration including: a plurality of elastic wave filters having different pass bands from each other; a common terminal to which at least one 1 st circuit element is connected between a connection path to the antenna element and the reference terminal, and to which at least one 2 nd circuit element is connected in series; and a1 st inductance element, wherein, of the plurality of elastic wave filters, an output terminal of the transmission side filter is connected to the common terminal via the 1 st inductance element connected to the output terminal and the common terminal, and is connected to the parallel resonator, and, of input terminals and output terminals of elastic wave filters other than the transmission side filter, a terminal on the antenna element side is connected to the common terminal, and is connected to a series resonator of the series resonator and the parallel resonator. Thus, even when the characteristic impedance is different between the transmission terminal or the reception terminal side and the antenna terminal side of the surface acoustic wave filter, the impedance can be sufficiently matched. Therefore, even if the number of frequency bands and the number of modes to be handled are increased, a low-loss multiplexer can be provided.
Industrial applicability
The present invention is widely applicable to communication devices such as mobile phones as a low-loss multiplexer, a transmission device, and a reception device that can be applied to frequency standards that are multi-banded and multi-modal.

Claims (10)

1. A multiplexer for transmitting and receiving a plurality of high frequency signals via an antenna element,
the multiplexer includes:
a plurality of elastic wave filters having different pass bands from each other;
a common terminal to which at least one 1 st circuit element is connected between a connection path with the antenna element and a reference terminal, and to which at least one 2 nd circuit element is connected in series; and
the inductance component of the 1 st order inductor,
each of the elastic wave filters includes at least one of a series resonator connected between an input terminal and an output terminal, and a parallel resonator connected between a connection path connecting the input terminal and the output terminal and a reference terminal,
one of the input terminal and the output terminal of one of the plurality of elastic wave filters, which is close to the antenna element, is connected to the common terminal via the 1 st inductance element connected to the one of the input terminal and the output terminal, and is connected to the parallel resonator,
among the plurality of elastic wave filters, one of an input terminal and an output terminal of an elastic wave filter other than the one elastic wave filter, which is close to the antenna element, is connected to the common terminal and to the series resonator,
a real part of a characteristic impedance of the multiplexer as viewed from the common terminal is 50 Ω or more, the 1 st circuit element of the 1 st circuit element and the 2 nd circuit element is connected so as to be close to the common terminal, the 1 st circuit element is a capacitive element, and the 2 nd circuit element is an inductive element.
2. The multiplexer of claim 1, wherein,
the 1 st inductance element is connected to one terminal of the one elastic wave filter close to the antenna element, and the impedance of the one elastic wave filter in a frequency band other than the self frequency band is inductive.
3. The multiplexer of claim 1 or 2,
the characteristic impedance of a terminal on the opposite side of one of the input terminal and the output terminal of the plurality of elastic wave filters, which is close to the antenna element, is different from that of the other terminal.
4. The multiplexer of claim 1 or 2,
the other elastic wave filter, which requires isolation from the one elastic wave filter, among the plurality of elastic wave filters, has a 2 nd inductance element in series or in parallel with a terminal on a side opposite to one terminal close to the antenna element.
5. The multiplexer of claim 1 or 2,
a complex impedance in a predetermined pass band when the single elastic wave filter is viewed through the 1 st inductance element in a state where the 1 st inductance element and one of the input terminal and the output terminal of the one elastic wave filter which is close to the antenna element are connected in series, and a complex impedance in the predetermined pass band when the elastic wave filter other than the one elastic wave filter is viewed from the side of one of the input terminal and the output terminal which is close to the antenna element and is connected to the common terminal in a state where the one of the input terminal and the output terminal of the elastic wave filter other than the one elastic wave filter which is close to the antenna element is connected to the common terminal are in a complex conjugate relationship.
6. The multiplexer of claim 1 or 2,
the piezoelectric substrate that constitutes each of the plurality of elastic wave filters includes:
a piezoelectric film having an interdigital transducer electrode (IDT) electrode formed on one surface;
a high acoustic velocity support substrate that propagates a bulk acoustic velocity higher than an elastic acoustic velocity propagating in the piezoelectric film; and
and a low acoustic velocity film disposed between the high acoustic velocity support substrate and the piezoelectric film, the low acoustic velocity film having a bulk acoustic velocity lower than an elastic acoustic velocity propagating through the piezoelectric film.
7. The multiplexer of claim 1 or 2,
the multiplexer includes, as the plurality of elastic wave filters:
the elastic wave filter of 1 st, having a1 st pass band, outputting a transmission signal to the antenna element;
2 the elastic wave filter having a 2 nd pass band adjacent to the 1 st pass band, receiving a signal input from the antenna element;
the elastic wave filter of claim 3 having a 3 rd pass band located on a lower frequency side than the 1 st pass band and the 2 nd pass band, and outputting a transmission signal to the antenna element; and
the 4 th elastic wave filter having a 4 th pass band located on a higher frequency side than the 1 st pass band and the 2 nd pass band, receiving signals being input from the antenna elements,
the one elastic wave filter in which the 1 st inductance element is connected in series is at least one of the 2 nd elastic wave filter and the 4 th elastic wave filter.
8. A transmitting apparatus which receives a plurality of high frequency signals having carrier frequency bands different from each other, filters the plurality of high frequency signals, and wirelessly transmits the filtered high frequency signals from a common antenna element,
the transmission device includes:
a plurality of transmitting elastic wave filters that receive the plurality of high-frequency signals from the transmitting circuit and pass only a predetermined frequency band; and
a common terminal to which at least one 1 st circuit element is connected between a connection path with the antenna element and a reference terminal, and to which at least one 2 nd circuit element is connected in series,
each of the plurality of transmitting elastic wave filters includes at least one of a series resonator connected between an input terminal and an output terminal and a parallel resonator connected between a connection path connecting the input terminal and the output terminal and a reference terminal,
an output terminal of one of the plurality of transmission elastic wave filters is connected to the common terminal via an inductance element connected to the output terminal and the common terminal, and is connected to the parallel resonator,
an output terminal of a transmission elastic wave filter other than the one transmission elastic wave filter is connected to the common terminal and to the series resonator of the series resonators and the parallel resonators,
a real part of a characteristic impedance of the multiplexer as viewed from the common terminal is 50 Ω or more, the 1 st circuit element of the 1 st circuit element and the 2 nd circuit element is connected so as to be close to the common terminal, the 1 st circuit element is a capacitive element, and the 2 nd circuit element is an inductive element.
9. A receiving apparatus receives a plurality of high frequency signals having mutually different carrier frequency bands via an antenna element, and demultiplexes the plurality of high frequency signals to output the plurality of high frequency signals to a receiving circuit,
the receiving apparatus includes:
a plurality of reception elastic wave filters that input the plurality of high-frequency signals from the antenna element and pass only a predetermined frequency band; and
a common terminal to which at least one 1 st circuit element is connected between a connection path with the antenna element and a reference terminal, and to which at least one 2 nd circuit element is connected in series,
each of the plurality of reception elastic wave filters includes at least one of a series resonator connected between an input terminal and an output terminal, and a parallel resonator connected between a connection path connecting the input terminal and the output terminal and a reference terminal,
an input terminal of one of the plurality of reception elastic wave filters is connected to the common terminal via an inductance element connected to the input terminal and the common terminal, and is connected to the parallel resonator,
an input terminal of a reception elastic wave filter other than the one reception elastic wave filter is connected to the common terminal and to the series resonator of the series resonators and the parallel resonators,
a real part of a characteristic impedance of the multiplexer as viewed from the common terminal is 50 Ω or more, the 1 st circuit element of the 1 st circuit element and the 2 nd circuit element is connected so as to be close to the common terminal, the 1 st circuit element is a capacitive element, and the 2 nd circuit element is an inductive element.
10. An impedance matching method of a multiplexer that transmits and receives a plurality of high frequency signals via an antenna element, wherein,
the impedance matching method of the multiplexer comprises the following steps:
adjusting a plurality of elastic wave filters having different pass bands such that complex impedances in pass bands of the other elastic wave filters become a short-circuited state when the single elastic wave filter is viewed from one of an input terminal and an output terminal of the single elastic wave filter, and complex impedances in pass bands of the other elastic wave filters become an open-circuited state when the single elastic wave filter is viewed from one of the input terminal and the output terminal of the elastic wave filter other than the single elastic wave filter, among the plurality of elastic wave filters;
adjusting an inductance value of the filter-matching inductance element so that a complex impedance when the one elastic wave filter is viewed from the filter-matching inductance element side when the one elastic wave filter is connected in series to the filter-matching inductance element and a complex impedance when the other elastic wave filter is viewed from the common terminal side when the other elastic wave filter other than the one elastic wave filter is connected in parallel to the common terminal are in a complex conjugate relationship;
adjusting at least one 1 st circuit element connected between a connection path of the antenna element and the common terminal and a reference terminal, and at least one 2 nd circuit element connected in series to a connection path of the antenna element and the common terminal so that a complex impedance seen from the common terminal of a synthesis circuit in which the one elastic wave filter is connected to the common terminal via the filter-matching inductance element and the other elastic wave filters are connected in parallel to the common terminal is matched with a characteristic impedance,
in the step of adjusting the plurality of elastic wave filters, one of the plurality of elastic wave filters including a series resonator connected between an input terminal and an output terminal and a parallel resonator connected between a connection path connecting the input terminal and the output terminal and a reference terminal is arranged such that the parallel resonator and the series resonator are connected to the filter matching inductance element in the one elastic wave filter and the parallel resonator and the series resonator are arranged such that the series resonator among the parallel resonator and the series resonator is connected to the common terminal in the other elastic wave filter,
a real part of a characteristic impedance of the multiplexer as viewed from the common terminal is 50 Ω or more, the 1 st circuit element of the 1 st circuit element and the 2 nd circuit element is connected so as to be close to the common terminal, the 1 st circuit element is a capacitive element, and the 2 nd circuit element is an inductive element.
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